While spacecraft previously sent to the Red Planet have discovered hints of dirt in the Martian crust, astronomers had no direct evidence of the dust present on the planet until the Phoenix Lander completed its 422-million mile journey on Sunday evening.

Phoenix Mars project director Barry Goldstein said at a press conference early Monday morning that the implications were enormous.

"Not only do we have evidence that there was dirt on the surface of Mars billions of years ago, but these images clearly show that dirt can still be found there in abundance," he said. "Other missions have only hinted at the sheer volume of rocks and soil on Mars."

"Follow the dirt" has been NASA's motto for Mars exploration since the 1970s, and missions to the planet have radically challenged prior understandings of the planet. The agency's Viking landers stunned astronomers by finding what Carl Sagan described as a "awhole goddamn lot of rocks" in 1976. Subsequent missions, including the Spirit and Opportunity rovers, have yielded even more suggestions of the existence of dirt on Mars.

After a diagnostic check, Phoenix will deploy a robotic arm to analyze the composition of dirt, and whether it is wet, damp or dusty.

"This raises profound questions," Goldstein said. "Earth, it seems, is not the only place one can find dirt in abundance."

Of the $420 million spent on the dirt-confirming mission, $37 million contributed to a built-in weather station, which will soon reveal whether the climate of Mars is typically sunny or windy, or possibly even both.

The next major NASA mission will be the Jupiter Zeus Flyer, a $798 million mission to confirm that there is gas on Jupiter.